Book Review: Darwin's Doubt: The Explosive Origin of Animal Life and the Case for Intelligent Designby Rich Deem

Book Review

Synopsis:
Cambrian explosion and intelligent designSummary: Darwin's Doubt is a comprehensive examination of the Cambrian Explosion, based upon the results from the latest scientific studies. Stephen Meyer takes us through the fossil record of the Ediacaran and Cambrian periods along with genetic evidence related to the topic. showing that there is no
realistic scientific explanation that delineates the rise of animal body plans.

Rating:

Rich Deem

Introduction

Darwin's Doubt: The Explosive Origin of Animal Life and the Case for Intelligent Design
is the new book by Stephen Meyer of the Discovery Institute. The book's title is taken
from Charles' Darwin's concern that his theory could not explain the lack of
potential ancestors of animals appearing prior to what has been called the
Cambrian explosion. During this brief period of time (~10 million years),
numerous phyla (the highest classification scheme below "kingdom") of complex animals with novel body plans suddenly appeared from
nowhere. Although additional classes of animals appeared subsequent to the
Cambrian explosion, all animal phyla (both extant and extinct) originated at
that time. So, is the Cambrian explosion still a problem for neo-Darwinian
evolution?

Cambrian conundrum

Charles Darwin and most scientists who believe in the neo-Darwinian theory
of biological evolution expect that the fossil record should show gradual
evolutionary diversity at the species and genus level followed by the
evolution of new biological families, orders, classes, and then phyla.
However, the Cambrian explosion turns that idea on its head, with a rapid
evolution of phyla followed by diversification of new orders, family, and
species. In other words, the big leaps in organism design came before
speciation, which is completely contrary to what gradualism would predict.

Attempts to discredit the Cambrian fossils

Several different attempts were made by evolutionists to discredit the problem
posed by Cambrian explosion fossils. Even early on, Darwinists attempted to
classify radically different animals into existing phyla in an attempt to
minimize the obvious the diversity of the fossil evidence. Later efforts
hypothesized that pre-Cambrian fossils just hadn't been found yet or that
the soft-bodied ancestors of the Cambrian fauna just hadn't fossilized. All
these attempts to minimize explosive nature of the Cambrian fossil evidence
were shown to be false, since exquisitely-preserved soft-bodied animals,
including sponge embryos showing cell nuclei, were shown to be preserved in
Cambrian sedimentary rock.

Still other Darwinists have cited the appearance of fossils in the Ediacaran
period, immediately prior to the Cambrian. These fossils represent a radical
leap from previous life on earth, which was purely single-celled organisms.
However, the phyla represented could account for, at most, only four of the
twenty phyla that appeared during the Cambrian explosion. In addition, these
organisms lack the innovative designs of the Cambrian, such as eyes, heads,
mouths, guts, and spinal cords.

Molecular Clock

Based upon the concept of a molecular clock in the genetic sequences of key
genes of Cambrian ancestors, scientists have attempted to calculate the time
at which these hypothetical ancestors must have evolved. Since the fossil
record failed to demonstrate these pre-Cambrian ancestors, scientists had
hoped to raise doubt on the brevity of the Cambrian explosion. Calculations
based upon a molecular clock showed that these hypothetical ancestors must
have arisen a billion or more years ago (half a billion before the Cambrian
explosion). However, there isn't even a hint of multicellularity that far back, even though we can find fossil evidence of
single-celled organisms as far back as 3.5 billion years ago. Molecular
clocks based upon different proteins in different studies produce divergence
dates that vary by more than 1 billion years. Hence, the accuracy of such
studies must be questioned.

New Genes

Darwin's Doubt
contains a number of chapters dedicated to the question of how new
information and new genes can arise, which might explain the mechanism
behind the Cambrian explosion. The problem is not as simple as it
might seem at first, since not only were new body plans developed, but
dozens of new kinds of organs, tissues and cell types for all those body
plans. Such massive innovations require the addition of thousands of new
genes that are perfectly integrated with each other in order to
produce an organism that functions. The Darwinian explanations for the
origin of genetic information would be hard-pressed to explain how all those
new designs appeared. Although the chapters in "How to build an animal" tend
to be thorough, I would have preferred to see a better rebuttal to the
primary Darwinian mechanism cited for the appearance of new genes—exon shuffling.

Embryology

Scientists have learned a lot by studying fruit flies. The use of
mutation-causing chemicals during development have demonstrated what genes
are important during the development of fruit fly larva. However, virtually
all the mutations that affect embryogenesis produce fruit flies that are
either non-viable or severely compromised. Better adapted fruit flies are
never produced. So, there is a question as to how mutation can ever select a
better adapted individual. Since macroevolution is dependent upon mutations
that change the body plans of species, mutations that do so must impact
development early in the process. However, these kinds of mutations are
almost always deleterious.

Conclusions

Darwin's Doubt
is a really good, comprehensive examination of the Cambrian explosion and
its implication regarding the neo-Darwinian model of evolution. As in Meyer's
Signature in the Cell, the
book is heavily referenced for those who want to explore topics more thoroughly.
Darwin's Doubt
tends to be somewhat more technically challenging, but not beyond the
ability of the average science enthusiast to understand. One of the strengths of
the book is that it thoroughly covers the numerous naturalistic models that
attempt to explain the origin of new biological information. It has been a great
help to me in helping to elucidate the numerous naturalistic models proposed to
explain the diversity of life and the fossil record.